Pulse gate



Jan. 25, 1966 H. B. DIAMANT 3,231,758

PULSE GATE Filed Dec. 12, 1962 TR1-1- l T1 ATTORN E YS ticula'rlyv relates to a self-powered gate.

United States. Patent *O sary to modify or add to thelogical systems of'computers i form in response to the signals which appear onterminals of a program panel and does Anot"require"additional pow- .er sources. e g

An object of this invention is `to provide a pulse gate which does not require: an externalfpower supply and which will perform properly as a pulse coincidence gate or AND circuit as a logical element coupled to the program panelof a standard accounting machine.

Another object of this invention is to provide a selfpowered gating circuit. c. e

Still another object of this invention is to provide aself# powered latching circuit which produces output signals depending upon the state of predetermined input signals.

Still another object of my invention is to provide a sel'fapowered AND circuit which responds to coincidence of a predetermined number of m input signals where it is possible to have ninput signals. j e Y p Briefly, my invention comprises solid state circuit means having at least three electrically coupled pn junctions and i three external terminals connected' thereto. One external necting circuitry.A One of the inputs isappl'ied to an intermediate pn junction and comprises the trigger input. The signal inputs are obtained directly from operating circuitry such as predetermined terminalsV on` a program panel board of a standardcomputer. After coincidence of the input signals, the solid state circuit means remains energized. That is, the solidstate means remain on after C of this invention and the manner of attaining" themwill become more apparent andthe invention itself willy be best urerstood by reference to the ,following description of embodiments of the invention taken in conjunction with the accompanying drawing, in whichcuit of my invention shown connected to a load;

FIGURE 2` is a schematic drawing of a preferred embodiment of the invention usinga silicon control rectifier; FIGURE 3 is an alternative embodiment' aswell as an oit when the other FIGURE' 1 is a simple' bl'o'ck diagram ofthe-AND cir- 3,231,758 Patented Jan.`25, 1966 equivalent circuit of the embodiment of FIGURE 2 using two standard junctiontransistors;

FIGURE 4 is still another embodiment o f thisinvention` ,employingv a plurality of input resistors for providing ANI) resistor logici Y e FIGURE 5 is a simplified diagram of the characteristics of nic sono state device of this invention;

FIGURE 6 is a ,pulse timing diagram showing thc e pins and ootpufof iiiy invention.

Referring now to'FIGURE 1", there is shown an AND circuit 1` and a load `2. `The AND circuit 1 is shown iii more detail Vin FIGURES 2 4. The output of the AND circuit 4 is connected directly to the load 2, the other terminar of which may he connected to a reference level terminal 5 which may be ground. The input terminals 6 'and 8 are designated as IN and TRIGGER indicating their respective functions. I The voltage or' current level applied to each' terminal 6, 8 may 'be the sar'ne' and may be taken from terminals of the program panel board as previously explained. y

e, The AND' circuit will turn on Vonly when `input `and trigger signals are simultaneously applied and when a load is connected. The AND gate will` remain on regardless of the signal level at trigged input 8 and turns ol onlygwhen either the input signal at 6 is terminated or departs from its prescribed state or when the load is disconnected. Since any circuit becomes inoperable when it is opened, it will be assumed as evident that removal of the load will dee'ne'rgize 'the ci" and 'this will not beV referred to further as alim'iting fr.

Referring t6 FIGURE 2, there is shv'v'n a four layer did 10' s' silicon lCwt'ifl'ffcl rectifier `(2"Nl882') llt'or' fcri'nal 12, baise or conli term'r'l 14 "d t'e'llftA iifl 16. InputV 6 is CmeCteCl t ''ll'c't Vfiiil 12 ffftg'h fWardlY biased rectifier 18 while trigger input 8 is coupled t base 14 tlJrOu'gl bas' I'S'Sr' 20. A bfS'-e'itf' sistr 22 connects th'e base and emitter terminals; The collector terminal 12 is also' connected to the emitter terminal 16 by rneansof 'parallel circuit 24 comprising backwardly biased'rectitier 26 and capacitor 28 (0.1 at). l

The equivalent circuitas well as an alternative embodirnen't of the circuit of FIGURE 2 isshown FIGURE 3 and comprises-'PNP Itransistor 30 and NPN transistor 32 connected` in feedback relationship. The two PN junctions of transistor 30l correspond to the upper and intermediate PN junctions of four layer diode 10 while the two PN junctions of transistor 32 correspond to the said intermediate and lower PN junctions of the four layer diode.

e The' operation of circuits of FIGURES 2 and 3v may be further understood `by `recognizing that the middle PN junction ofA four layer diode 10`l is shared and is common to` the PNP :and NPN transistor. As shown, there are tivo forwardly biased diodes and 18 connected be-` tween IN terminal 6 Aand; the emitter of PNP transistor 30. The base of transistor 30 is connected to the collector of NPN transistor 32 by conductor 34' while the collector of transistor 30 is connected to the base of transistor 32 by .conductor 34 to complete the feedback loopj. A stabilizing resistor 42 is connected from conductor 34 to a terminal between diodes 18 and 18'; Parallel circuit 24. is connected from the emitterhof transistor 32 to the terminal between diodes` I8 and 18"- A load 2 is connected to the emitter of transistor 32.

A trigger signal on lead 8 and applied tothe base of NPN transistor 3:2` (FIGURE 3) wil-1 be amplified and applied to the base of PNP transistor 30A over lead 34'; The output from the collector of transistor 30 is fed back over lead 34 to .the base of transistor 32. This feedback operation continues causing breakdown unless the voltage level at the emitter of transistor 30 is so low such that the emitter is negative with respect to the base. A more detailed discussion of the operation of the four layer diode may be found in Joyce and Clark, Transistor Circuit Analysis, page 199 (1961).

The characteristic of the four layer diode 10 is well known and is shown for illustration purposes in FIGURE 5. The characteristic resembles that of a thyratron inasmuch as breakdown is essentially a function of two voltages. When the input voltage reaches the breakdown level as illustrated and the trigger voltage is at a predetermined level, breakdown will occur. The dotted level Vb is intended to suggest that a much higher or ultimate breakdown voltage would be required if the trigger voltage were not at the predetermined threshold value. It will be seen that if the input and trigger voltage are coincidentally at the upper operating levels indicated at FIGURE 5, breakdown occurs. When the trigger voltage ceases the pulse gate remains on. However, the presence of only one of the Itwo input voltages below an ultimate level Vb' will not be sufcient to start conduction.

The operational characteristics of this invention may be seen by referring to FIGURE 6. The initiation of the IN signal will not cause any output until the trigger signal is applied.` Yet, when the trigger signal stops, the output does not change until the 1N signal ceases.

Specific examples of circuit elements from one embodiment of this invention are here illustrated:

An alternative embodiment of this invention employing resistor AND logic for controlling the threshold of the trigger signal is shown in FIGURE 4. FIGURE 4 differs from FIGURES 2 and 3 in the use of a Zener diode 37 in series connection with a current resistor 36 which is connected across the semiconductor device as well as in using a high resistance 38 in series with resistor 22. A predetermined number of resistors R1, R2, R3 Rx1 have one end connected to respective input signal sources and have their other end connected to common terminal 40. These resistors form esentially an adding circuit. Zener diode 37 in conjunction with base emitter resistor 38 provides a threshold Abias which must be overcome by the sum of the inputs which appears at terminal 40. When a signal appears on IN terminal 6, Zener diode 37 is broken down and establishes a current path therethrough. The break-down voltage over the Zener diode establishes the bias.

The particular bias which must be overcome may be judiciously selected in accordance with the number of input signals which are desired. Hence, the circuit may be designed so that every one of the inputs which is to be applied to resistors R1 Rn must be present or it may be desired that only a predetermined number m of the total number n possible signals must be present to overcome the bias.

My pulse gate under specific conditions performs some very useful latching and unlatching functions since it latches on or follows the state of one of the input signals and then turns E and responds to a predetermined condition of the other.

Semi-conductor devices which exhibit thyratron type characteristics may be used in connection with the principles of this invention in place of the multi-junction semiconductive means heretofore described.

While the foregoing description sets forth the principles of the invention in connection with specific apparatus, it is to be understood that this description is made only by way of example and not as a limitation of the scope of the invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. An AND gate whose output is energized when an input and a control voltage are simultaneously in a prescribed state and whose output is thereafter deenergized only when a predetermined one of said inputs departs from said prescribed state,

said gate being powered only by said rst and second inputs, l said AND gate comprising multiple unit semi-conductor means comprising at least three PN junctions, the N terminal of a first junction being coupled to the P terminal of a second junction, and the N terminal of the second junction being coupled to the P terminal of the third junction,

input voltage means coupled across the P terminal of said first junction and the N terminal of said third junction to forwardly bias said first and third junctions and rearwardly bias said second junction,

control voltage means coupled to said second junction,

said semi-conductor means having a breakdown voltage threshold which is a function of the control voltage, and said semiconductor means having a hold voltage threshold,

said input voltage being less than said breakdown voltage in the absence of a prescribed state of said control voltage, but suliicient to cause breakdown when said control voltage is in said prescribed state, said prescribed state being above said hold voltage,

' and adding means having a plurality of inputs coupled to said control voltage means to produce a signal of threshold level when a predetermined number of inputs are present,

said input voltage means including .a forwardly biased diode connected to said P terminal,

said control voltage means including a first series resistor, and a second resistor connected from said first series resistor to said N terminal of said third junction, a load lconnected from said N terminal of said third Junction and a parallel circuit comprising a capacitor and a reversely biased diode connected from the P terminal of the first junction to the N terminal of the third junction,

said input voltage means including a Zener diode coupled between said second and third junctions, whereby when an input voltage is applied, said Zener diode is operated at breakdown level and thereby the threshold level for said control signal is reduced.

2. An AND gate whose output is energized when an inp'ut and a control voltage are simultaneously in a prescribed state and whose output is thereafter deenergized only when a predetermined one of said inputs departs from said prescribed state,

said gate being powered only by said first and second inputs,

said AND gate comprising multiple unit semi-conductor means comprising at least three PN junctions, the N terminal of a first junction being coupled to the P terminal of a second junction, and the N terminal of the second junction being coupled to the P terminal of the third junction,

inputvoltage means coupled across the P terminal of said first junction and the N terminal of said third 5 j 6 junction to forwardly bias said first and `third juncsistor, and a second resistor connected from said iirst tions and rearwardly bias said second junction, series resistor to said N terminal of said third junccontrol voltage means coupled to said second junction, tion, said semi-conductor means having a breakdown volta load connected from said N terminal of said third age threshold which is a function of the control 5 junction voltage, and said semi-conductor means having a hold and a parallel circuit comprising a capacitor and a revoltage threshold, versely biased diode connected from the P terminal said input voltage being less than said breakdown of the iirst junction to -the N terminal of the third voltage when said control voltage is not in said prejunction, scribed state, ,j 10 said input voltage being suciently large to cause break- References Cited by the Examiner down when said control voltage is in said prescribed UNITED STATES PATENTS state, said rescribed state being above said hold voltage, 2655609 10/1953 Shockley -r 307-885 said input voltage means including a Zener diode cou- 15 3,065,360 11/1962 Vallese 307-'88'5 led between said second and third junctions, wheregy when an input voltage is applied, said Zener OTHER REFERENCES diode is operated at breakdown level and thereby Application and Circuit Design NOCS, Solid State the threshold level for said control signal is reduced, Products, Inc., Bulletin D420-02, pages 4, l5, 19 and 20, :said input voltage means including a forwardly ybiased 20 December 1959.

diode connected to said P terminal, said control voltage means including a first series re- ARTHUR GAUSS, Primary Examiner- 

2. AN AND GATE WHOSE OUTPUT IS ENERGIZED WHEN AN INPUT AND A CONTROL VOLTAGE ARE SIMULTANEOUSLY IN A PRESCRIBED STATE AND WHOSE OUTPUT IS THEREAFTER DEENERGIZED ONLY WHEN A PREDETERMINED ONE OF SAID INPUTS DEPARTS FROM SAID PRESCRIBED STATE, SAID GATE BEING POWERED ONLY BY SAID FIRST AND SECOND INPUTS, SAID AND GATE COMPRISING MULTIPLE UNIT SEMI-CONDUCTOR MEANS COMPRISING AT LEAST THREE PN JUNCTIONS, THE N TERMINAL OF A FIRST JUNCTION BEING COUPLED TO THE P TERMINAL OF A SECOND JUNCTION, AND THE N TERMINAL OF THE SECOND JUNCTION BEING COUPLED TO THE P TERMINAL OF THE THIRD JUNCTION, INPUT VOLTAGE MEANS COUPLED ACROSS THE P TERMINAL OF SAID FIRST JUNCTION AND THE N TERMINAL OF SAID THIRD JUNCTION TO FORWARDLY BIAS SAID FIRST AND THIRD JUNCTIONS AND REARWARDLY BIAS SAID SECOND JUNCTION, CONTROL VOLTAGE MEANS COUPLED TO SAID SECOND JUNCTION, SAID SEMI-CONDUCTOR MEANS HAVING A BREAKDOWN VOLTAGE THRESHOLD WHICH IS A FUNCTION OF THE CONTROL VOLTAGE, AND SAID SEMI-CONDUCTOR MEANS HAVING A HOLD VOLTAGE THRESHOLD, SAID INPUT VOLTAGE BEING LESS THAN SAID BREAKDOWN VOLTAGE WHEN SAID CONTROL VOLTAGE IS NOT IN SAID PRESCRIBED STATE, SAID INPUT VOLTAGE BEING SUFFICIENT LARGE TO CAUSE BREAKDOWN WHEN SAID CONTROL VOLTAGE IS IN SAID PRESCRIBED STATE, SAID PRESCRIBED STATE BEING ABOVE SAID HOLD VOLTAGE, SAID INPUT VOLTAGE MEANS INCLUDING A ZENER DIODE COUPLED BETWEEN SAID SECOND AND THIRD JUNCTIONS, WHEREBY WHEN AN INPUT VOLTAGE IS APPLIED, SAID ZENER DIODE IS OPERATED AT BREAKDOWN LEVEL AND THEREBY THE THRESHOLD LEVEL FOR SAID CONTROL SIGNAL IS REDUCED, SAID INPUT VOLTAGE MEANS INCLUDING A FORWARDLY BIASED DIODE CONNECTED TO SAID P TERMINAL, SAID CONTROL VOLTAGE MEANS INCLUDING A FIRST SERIES RESISTOR, AND A SECOND RESISTOR CONNECTED FROM SAID FIRST SERIES RESISTOR TO SAID N TERMINAL OF SAID THIRD JUNCTION, A LOAD CONNECTED FROM SAID N TERMINAL OF SAID THIRD JUNCTION AND A PARALLEL CIRCUIT COMPRISING A CAPACITOR AND A REVERSELY BIASED DIODE CONNECTED FROM THE P TERMINAL OF THE FIRST JUNCTION TO THE N TERMINAL OF THE THIRD JUNCTION. 